This study was designed to evaluate the impact on the quality of pathology reports of a cancer network, named R2c covering the west side of PACA region. Over a 7 year-period, we collected 4521 pathology reports on primary breast cancers, filled by pathologists belonging or not the network. The analysis focused on the 6 histo-prognostic factors from the pathology report standardized according to European recommendations. Between the 1997 and 2003 the proportion of reports filled for the 6 factors increased from 29,6 % to 75,1 % among non-member, and from 49,1 % to 89,7 % among members. The histological size or the number of nodes examined is however filled similarly in these two groups. This study shows how the direct implication of the pathologists in a network, with precise criteria improves quality of reports. Nevertheless, network participation is not the only cause of improvement. Having a clinical practice corresponding to the standards determines partly the involvement in a network aiming at rationalizing practices. Moreover, centralised data collection carried out by R2c allows an annual evaluation of the quality of the reports, providing feedback information to members. Lastly, the shared liability in oncology probably has an indirect impact on practices of non-member pathologists.